This competing application for a training program in Immunology and Pathogenesis (IMP) supports the training activities of 15 field-leading scientists whose research centers on immunobiology. The training faculty are all members of the Department of Molecular and Cell Biology (MCB), and each has ample research support and a strong commitment to mentoring. The training program is centered in the MCB Division of Immunology and Pathogenesis, in which most training faculty are members. The IMP Training program focuses on basic immunological mechanisms in the context of infections, cancer and immunopathology. We are motivated by the shared belief that achieving a thorough, basic understanding of recognition, activation, regulation, differentiation and interactions of cells of the immune system will lead to therapies for infectious disease, cancer and other ailments, and that training young investigators in this approach, while providing broad training in basic molecular and cell biology, offers a most productive avenue for enhancing success in this endeavor. The program is strongly committed to recruiting and training students and postdocs from diverse personal backgrounds. The IMP training program will provide a home for trainees in Immunology and Pathogenesis and support for training related activities. We propose support for 4 graduate students and 3 postdoctoral fellows. Graduate students will generally be supported starting in their second year to ensure commitment to the research area and to provide additional information to evaluate their capability of providing exceptional contributions to the program. Postdoctoral trainees will generally be supported starting in their first or second year. In general trainees will be supported for 2 years on the training grant, with additional years supported from other sources. While this training grant is currently in its 5th year, the grant is the successor of an NCI-supported training grant (Molecular Immunology and Tumor Biology Training Program, T32 CA009179), which supported immunology research at Berkeley for 35 years.